Semiconductor light emitting devices are used for illumination, for example as automobile head lamps. For example, semiconductor light emitting diode arrays (LED arrays) including a plurality of semiconductor light emitting diode elements (LED elements) connected in series, or in parallel, or in parallel and in series are used as the semiconductor light emitting devices (for example, see Japanese Laid-open Patent Publication No. 2001-156331).
FIG. 5 shows a cross section of a conventional LED array 200. An LED array 200 has a structure in which a plurality of gallium nitride series semiconductor light emitting diode elements (LED elements) 201 are disposed on a support substrate 210. Here, the term “gallium nitride series” means group III-V compound semiconductor AlxGayInzN (0<or=x<or=1, 0<or=y<or=1, 0<or=z<or=1, x+y+z=1).
Respective LED elements are, for example, blue light emitting elements, each having at least a GaN series light emitting part 202 including an n-type GaN layer, an active layer, and a p-type GaN layer, a reflection electrode 203 formed for example of Ag or Al on a rear surface of the light emitting part 202, a wiring layer 208 disposed on a front surface of the light emitting part 202 for diffusing current supplied from a current supply pad into the light emitting part 202, and a melt adhesion layer 206 for connecting the reflection electrode 203 and the support substrate 210.
A yellow fluorescent material (phosphor) layer 218 formed of a transparent resin including yellow fluorescent (phosphor) powder 219 is coated on the surface of the LED elements 201. White lights can be emitted from the LED array 200, by the combination of blue light emitting LED elements 201 and the fluorescent layer 218 containing yellow fluorescent powder 219.
In the LED array 200, a plurality of LED element regions (EL) 201 are separated by an intervening region (isolating groove or street ST). The fluorescent layer 218 fills the street ST as well as covering the LED elements 201. The amount of fluorescent powder 219 at the street ST becomes higher than that on the LED element 201. Further, there is no blue light emission at the street ST. Therefore, the lights L1 emitting from the street ST become more yellowish (color temperature becomes lower) than the lights L2 emitting from the LED element region EL. Therefore, the conventional LED array 200 may produce uneven color distribution.
Also, lights emitting from the street ST are low since there is no light emitting element. Therefore, the conventional LED array may produce uneven brightness distribution.